RSA Security 5.2.2 Indicates type of base field, It is the prime number, Cofactor of the subgroup

Performing Elliptic Curve Operations

Type of information this allows you to use:

the parameters generated by executing AI_ECParamGen for either generating keys or executing key agreements.

The Reference Manual Chapter 2 entry for AI_ECParameters also states that the format of the information returned by B_GetAlgorithmInfo is a pointer to an A_EC_PARAMS structure:

typedef struct	{
unsigned int	version;	/* implementation version */
unsigned int	fieldType;	/* indicates type of base field */
ITEM	fieldInfo;	/* It is the prime number */
		/* in case that fieldType = FT_FP; */
	/* the basis polynomial if fieldType = FT_F2_POLYNOMIAL; */
	/* and the degree of the field if fieldType = FT_F2_ONB */
ITEM	coeffA;	/* elliptic curve coefficient */
ITEM	coeffB;	/* elliptic curve coefficient */
ITEM	base;	/* elliptic curve group generator */
ITEM	order;	/* order of subgroup’s generating element */
ITEM	cofactor;	/* the cofactor of the subgroup */
unsigned int	pointRepresentation; /* not used. */
		/* set to CI_NO_COMPRESS as a default */
unsigned int fieldElementBits;		/* field element size in bits */
} A_EC_PARAMS;

Assume that the elliptic curve parameters are placed in the algorithm object ecParamsObj (see “Generating Elliptic Curve Parameters” on page 260). Make the appropriate call to B_GetAlgorithmInfo:

A_EC_PARAMS *cryptocECParamInfo;

if ((status = B_GetAlgorithmInfo((POINTER *)&cryptocECParamInfo, ecParamsObj, AI_ECParameters)) != 0)

break;

Note that cryptocECParamInfo is a pointer to the information, not the information itself. The memory that cryptocECParamInfo points to belongs to Crypto-C; another call to Crypto-C may alter or destroy it. Therefore, once you get the pointer to the information, you must copy it to your own buffer.

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